Conventional mixing cartridges for single-lever mixing faucets generally comprise a substantially cylindrical container, which accommodates a base disk, made of ceramic material, arranged proximate to one of the bases of the container and crossed by three ports, respectively an intake port that can be connected to a duct for feeding hot water, another intake port that can be connected to a duct for feeding cold water, and a discharge port that can be connected to a dispensing outlet of the faucet in the body of which the cartridge is fitted.
The base disk usually rests with one of its faces against one of the bases of the container, and such base is crossed by three holes that are connected to the three ports. A mixing disk made of ceramic material is slidingly coupled to the opposite face of the base disk.
Such mixing disk has, on its side directed toward the base disk, a recess, a portion of which is usually constantly connected to the discharge port.
The mixing disk can slide on command with respect to the base disk both with a translational motion on the plane on which it is coupled to the base disk and with a rotary motion about an axis that is perpendicular to the coupling plane.
By way of the translational motion, the mixing disk varies the passage sections of the intake ports that are connected to the recess, keeping their ratio constant so as to vary the flow-rate of dispensed water without varying the ratio between hot water and cold water, whilst by means of the rotary motion the mixing disk varies the ratio between the passage sections of the intake ports that are connected to the recess, accordingly varying the ratio between hot water and cold water.
The movement of the mixing disk is actuated by a lever that is supported by the container of the cartridge and is usually rotatable about the axis of the container and about an axis that is perpendicular to the axis of the container in order to produce the two movements of the mixing disk.
These mixing cartridges are accommodated and locked in an appropriately provided cavity formed in the body of mixing faucets. Usually, the bottom of this cavity, on which the base of the container of the cartridge with the three holes rests, is provided with the outlets of the ducts for feeding hot and cold water and the inlet of the duct that leads to the dispensing outlet of the faucet.
This construction of the mixing cartridges, with the two intake ports and the discharge port formed in a same base of the cartridge, has constrained considerably the design and styling of mixing faucets.
Up to now, in order to be free from the constraints imposed by mixing cartridges characteristics it was necessary to renounce their use and to deal with significantly higher faucet manufacturing and maintenance costs.